Basin drainage systems enable the draining of liquid from a liquid holding basin, such as a sink or tub, through to a plumbing system such as the centralized plumbing and waste removal systems ordinarily found in residential and commercial structures and shelters. Generally speaking, drainage systems include a drain which can be coupled to an orifice at or near the bottom of the basin. A plumbing system having a drain pipe can be coupled to the bottom of the basin from an opposite end of the orifice. Alternatively, the drain pipe can be coupled directly to an opposing end of the drain. In either case, a drainage port can be formed within the drain through which liquid in the basin can flow into the plumbing system. Notably, most drainage systems include a stopper or drain plug with which the flow through the drainage port can be restricted if not halted altogether.
U.S. Pat. No. 3,495,280 to Galbiati discloses a sink drainage system in which a collar protruding circumferentially from a drain can engage the interior portion of a sink at the sink orifice. As such, liquid can flow from the sink towards the drainage channel in the drain over the collar. U.S. Pat. No. 6,219,861 to Chen similarly illustrates a conventional drainage system in which a docking collar also can couple snuggly to the orifice of sink to allow the flow of liquid from the sink into the drain. Importantly, in both the case of Galbiati and Chen, it will be apparent to the skilled artisan that some liquid can become trapped at the intersection of the collar and the drain. Moreover, liquid can seep below the collar into the void between the sink orifice rim and the bottom of the collar.
When standing liquid is allowed to persist within the void of a drainage system, several undesirable conditions can result. Most notably, mold can form where the liquid is water. Also, where the liquid is corrosive in nature, the sink can rot in the vicinity of the drain orifice. In either case, at a minimum, an unattractive discoloration of the sink can develop giving the appearance of generally unsanitary conditions. Thus, it would be desirable to avoid the standing liquid problem associated with the docking collar of the conventional drainage system.